Anti‐striational antibodies: Expanding their clinical significance

Abstract

Myasthenia gravis (MG) is an organ-specific autoimmune disorder generally mediated by anti-acetylcholine receptor (AChR) or, less frequently, by anti-muscle-specific tyrosine antibodies at the neuromuscular junction. 1 In the 1970s, before the discovery of anti-AChR antibodies, anti-striational antibodies (StrAbs) were known as serum immunoglobulins that react with cross-striations of skeletal muscle in MG patients. Indirect immunofluorescence of animal skeletal muscle tissue was the original method for detecting StrAbs. 2 StrAbs had been expected to be useful as biomarkers of MG; however, immunoreactivity on indirect immunofluorescence was also observed in other disorders and in normal controls. Because of the low specificity of StrAbs as biomarkers, the diagnostic utility of StrAbs had been regarded to be limited. In the 1990s, several molecules on skeletal and heart muscle proteins were identified as autoantigens of StrAbs. In particular, the

Anti-Kv1.4 Antibody-positive Nivolumab-induced Myasthenia Gravis and Myositis Presenting with Bilateral Ptosis and Demonstrating Different Pathophysiologies

“…Several autoantibodies targeting titin, ryanodine receptors, and others have been detected in the serum of patients with idiopathic MG (32,33). Some of these antibodies have been associated with MG subtypes and disease severity (32,33), and patients with idiopathic MG who were positive for anti-Kv1.4 antibody generally showed a higher frequency of myasthenic crisis that was more severe than that in patients who were positive for anti-titin antibody (34)(35)(36). Recent case reports of irAE-MG have shown that patients with anti-Kv1.4 antibodies and anti-titin antibodies, as well as those with only anti-titin antibodies, also had a severe clinical course (21)(22)(23).…”

An Unusual Case of LGI1 (Leucine-Rich Glioma-Inactivated Protein 1) Limbic Encephalitis With Anti-acetylcholine Receptor and Anti-striational Autoantibodies

“…AChR antibodies target postsynaptic acetylcholine receptors found at the neuromuscular junction. Anti-striational antibodies target proteins such as titin and ryanodine receptors found in the cross-striations of skeletal and cardiac muscle [12]. The presence of AChR and anti-striational antibodies usually manifests as peripheral nervous system effects as commonly seen in myasthenia gravis, leading to symptoms such as weakness in the extremities and ptosis.…”